Conventionally, Type 1 diabetes has been treated with daily insulin injections. However, this inevitably results in insulin levels that do not match the normal and rapid changes in blood glucose which occur in a patient throughout the day. On the one hand, insufficient insulin and high glucose levels lead to immediate symptoms and contribute to long-term complications. On the other hand, too much insulin may result in too little blood sugar leading to loss of consciousness and convulsions. As an alternative to injections, insulin pump therapy is intended to mimic the normal physiology of the healthy pancreas. Unlike multiple daily insulin injections, an insulin pump is able to provide a constant background infusion of insulin that can be adjusted according to individual need, compensating for daily activity and exercise routines. The pump may also be programmed to deliver bolus doses of insulin to address the big glucose swings in the blood that would otherwise result from eating and drinking. By mimicking the natural physiology of the pancreas, insulin pump therapy aims to maintain a constantly normal blood glucose level; avoiding the highs that are associated with meals or the lows that come from too much insulin.
It is desirable, for reasons which will be explained subsequently, for the pump to be wirelessly controlled by a handset device. The pump, as a portable and therefore battery powered device, may run out of battery power, and a second pump device may be required while the original pump is being recharged. As a result, there is a need to provide for multiple pump devices which can be controlled by a single handset device. The use of more than one rechargeable unit with a single controller delivers a requirement that the user and the handheld device are aware that they are controlling the correct pump device. One way of achieving this would be to pre-pair handsets and a set of pump devices at the point of manufacture. However, handsets and pumps may be manufactured independently, making this solution impractical.